S-91251A939 1 1/4"-7 x 3 1/2" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance under extreme loads, reducing the risk of fastener failure in critical applications.
• Superior corrosion resistance provided by the black-oxide finish on alloy steel, extending service life in demanding industrial environments.
• High torque transmission capability with a 7/8" hex drive, allowing for secure installation and removal without stripping the drive.
• Coarse UNRC thread with Class 2A fit enables quick assembly and reliable holding power, minimizing cross-threading risks.
• Full threading along the 3 1/2" length offers versatile fastening depth and consistent clamping force across the entire engagement.
• Rockwell C37 hardness provides excellent wear resistance, maintaining thread integrity through repeated use.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety for global industrial use.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address common industrial challenges such as vibration loosening, high-stress fatigue, and corrosive environmental exposure. The coarse 1 1/4"-7 UNRC thread combined with a Class 2A fit provides rapid installation in heavy machinery, structural steel frameworks, and automotive assemblies where time efficiency and joint reliability are paramount. The alloy steel construction with 170,000 psi tensile strength ensures dependable performance in applications requiring high clamp load retention, such as industrial presses, conveyor systems, and construction equipment. The black-oxide surface treatment adds a protective layer against oxidation, making it suitable for both indoor and outdoor applications without compromising mechanical properties.

Specification Summary & Compliance

This socket head cap screw features precise Class 2A thread fit per UNRC standards, ensuring consistent engagement and dimensional accuracy. Manufactured in compliance with ASTM A574 specifications for high-strength alloy steel fasteners, it guarantees material integrity and performance repeatability. The product is fully RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting international environmental and safety regulations for industrial components.